spa city, western Czech Republic. The city lies along the Teplá River where it flows into the valley of the Ohře River, 70 miles (113 km) west of Prague. The surrounding highland areas were once subject to volcanic activity, which accounts for the thermal springs in the vicinity. Of more than a dozen active warm springs, the best-known and hottest, Vřídlo (German: Sprudel), gushes a geyser of hot water (162° F 【72° C】) to a height of 37 feet (11 m). The word teplá means “warm”; var means “boiling.”

Possibly known to the Romans, the spa was discovered or rediscovered and developed in about 1358 by Holy Roman Emperor Charles IV, and the town was chartered in 1370. The alkaline sulfur springs, valued for treating digestive disorders and liver diseases, were patronized by many medieval rulers, princes, noblemen, and ecclesiastics; visitors' books date from as early as 1569. Frequent guests of the spa included the composers Ludwig van Beethoven, Frédéric Chopin, Johannes Brahms, and Bedřich Smetana; the poets Johann Wolfgang von Goethe and Friedrich Schiller; and Tsar Peter I the Great. The spa's great popularity dates primarily from the 19th century, when the main baths, colonnades, hotels, and sanatoria were built. Before World War I it was a gathering place for Europe's wealthy invalids. The focal point of the modern spa is a colonnade that is the work of Josef Zítek, the Prague architect.

Industrial development associated with the expansion of coal mining nearby has resulted in air pollution that endangers the spa. Karlovy Vary's industries include the manufacture of porcelain and glassware, textiles and gloves; wafers and dietary biscuits and mineral salts are also produced. Pop. (2007 est.) 50,691.